Gliederung

Objective

Reduced activity of the potent anabolic effectors: insulin-like growth factor-I (IGF-I) and fibroblast growth factor-2 (FGF-2), play a role in aging associated muscle loss. The effect of fitness level on IGF-I and FGF-2 responses to all-out anaerobic exercise in older men was studied.

Results

At peak exercise, mean power output and serum lactate were higher (p<0.05) in the higher fit (446.0Â±14.9 kgm/min for mean Â±SD peak power and 12.6Â±1.1 mml/l for lactate) compared with the lower fit individuals (284.0Â±6.5 kgm/min and 8.5Â±0.7 mml/l, respectively). Pre-exercise IGF-I was lower and FGF-2 was higher in the higher fit (335.0Â±54.0 ng/ml and 1.6Â±0.1 pg/ml, respectively) compared with lower fit individuals (402.0Â±50.0 ng/ml and 1.4Â±0.2 pg/ml, respectively). Following the anaerobic exercise, in both groups, FGF-2 decreased dramatically (p<0.05); in the higher fit individuals FGF-2 level was 0.4Â±0.1 pg/ml compared to 0.1Â±0.02 pg/ml in the lower fit individuals. In contrast to FGF-2, IGF-I increased transiently to levels of 405.0Â±62.0 ng/ml in the higher fit individuals and to levels of 436Â±57.0 ng/ml in the lower fit individuals. However, the IGF-I elevation was significant (p<0.05) only in the higher fit individuals.

Conclusions

The present study demonstrates that during aging, fitness level can alter circulating levels of IGF-I and FGF-2. Furthermore, fitness level can affect the responses of both mediators to all-out anaerobic exercise.